trigger DeleteTask on Task (before delete) {
	
	List<String> meetingIds = new List<String>();
	
	for (Task t : trigger.old) {
		if (t.MeetingReport__c != null) {
			meetingIds.add(t.MeetingRecordId__c);
		}
	}
	
	if (meetingIds.size() > 0) {
		delete [Select Id From MeetingReport__c Where Id in :meetingIds];
	}
}